package com.xcj.common.threedes;

import java.io.UnsupportedEncodingException;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * SecretUtils {3DES加密解密的工具类 }
 * @author William
 * @date 2013-04-19
 */
public class SecretUtils {

	//定义加密算法，有DES、DESede(即3DES)、Blowfish
	private static final String Algorithm = "DESede";
	private static final String PASSWORD_CRYPT_KEY = "luguosujianaini123shanxisheng";

	/**
	 * 加密方法
	 * @param src 源数据的字节数组
	 * @return 
	 */
	public static byte[] encryptMode(byte[] src) {
		try {
			SecretKey deskey = new SecretKeySpec(
					build3DesKey(PASSWORD_CRYPT_KEY), Algorithm); //生成密钥
			Cipher c1 = Cipher.getInstance(Algorithm); //实例化负责加密/解密的Cipher工具类
			c1.init(Cipher.ENCRYPT_MODE, deskey); //初始化为加密模式
			return c1.doFinal(src);
		} catch (java.security.NoSuchAlgorithmException e1) {
			e1.printStackTrace();
		} catch (javax.crypto.NoSuchPaddingException e2) {
			e2.printStackTrace();
		} catch (java.lang.Exception e3) {
			e3.printStackTrace();
		}
		return null;
	}

	/**
	 * 解密函数
	 * @param src 密文的字节数组
	 * @return
	 */
	public static byte[] decryptMode(byte[] src) {
		try {
			SecretKey deskey = new SecretKeySpec(
					build3DesKey(PASSWORD_CRYPT_KEY), Algorithm);
			Cipher c1 = Cipher.getInstance(Algorithm);
			c1.init(Cipher.DECRYPT_MODE, deskey); //初始化为解密模式
			return c1.doFinal(src);
		} catch (java.security.NoSuchAlgorithmException e1) {
			e1.printStackTrace();
		} catch (javax.crypto.NoSuchPaddingException e2) {
			e2.printStackTrace();
		} catch (java.lang.Exception e3) {
			e3.printStackTrace();
		}
		return null;
	}

	/*
	 * 根据字符串生成密钥字节数组 
	 * @param keyStr 密钥字符串
	 * @return 
	 * @throws UnsupportedEncodingException
	 */
	public static byte[] build3DesKey(String keyStr)
			throws UnsupportedEncodingException {
		byte[] key = new byte[24]; //声明一个24位的字节数组，默认里面都是0
		byte[] temp = keyStr.getBytes("UTF-8"); //将字符串转成字节数组

		/*
		 * 执行数组拷贝
		 * System.arraycopy(源数组，从源数组哪里开始拷贝，目标数组，拷贝多少位)
		 */
		if (key.length > temp.length) {
			//如果temp不够24位，则拷贝temp数组整个长度的内容到key数组中
			System.arraycopy(temp, 0, key, 0, temp.length);
		} else {
			//如果temp大于24位，则拷贝temp数组24个长度的内容到key数组中
			System.arraycopy(temp, 0, key, 0, key.length);
		}
		return key;
	}

	public static void main(String[] args) {
		String msg = "xxx";
		System.out.println("【加密前】：" + msg);

		//加密
		byte[] secretArr = SecretUtils.encryptMode(msg.getBytes());
		System.out.println("【加密后】：" + secretArr);

		//解密
		byte[] myMsgArr = SecretUtils.decryptMode(secretArr);
		System.out.println("【解密后】：" + new String(myMsgArr));
	}

}